This invention provides benzoic acid and amide derivatives of anthranilic acids which inhibit certain dual specificity kinase enzymes involved in proliferative diseases such as cancer and restenosis.
Proliferative diseases are caused by a defect in the intracellular signaling system, or the signal transduction mechanism of certain proteins. Cancer, for example, is commonly caused by a series of defects in these signaling proteins, resulting from a change either in their intrinsic activity or in their cellular concentrations. The cell may produce a growth factor that binds to its own receptors, resulting in an autocrine loop, which continually stimulates proliferation. Mutations or overexpression of intracellular signaling proteins can lead to spurious mitogenic signals within the cell. Some of the most common mutations occur in genes encoding the protein known as Ras, which is a G-protein that is activated when bound to GTP, and inactivated when bound to GDP.
The above mentioned growth factor receptors, and many other mitogenic receptors, when activated, lead to Ras being converted from the GDP-bound state to the GTP-bound state. This signal is an absolute prerequisite for proliferation in most cell types. Defects in this signaling system, especially in the deactivation of the Ras.GTP complex, are common in cancers, and lead to the signaling cascade below Ras being chronically activated.
Activated Ras leads in turn to the activation of a cascade of serine/threonine kinases. One of the groups of kinases known to require an active Ras.GTP for its own activation is the Raf family. These in turn activate MEK, (eg, MEK1 and MEK2) which then activates MAP kinase. Activation of MAP kinase by mitogens appears to be essential for proliferation, and constitutive activation of this kinase is sufficient to induce cellular transformation. Blockade of downstream Ras signaling, for example by use of a dominant negative Raf-1 protein, can completely inhibit mitogenesis, whether induced from cell surface receptors or from oncogenic Ras mutants. Although Ras is not itself a protein kinase, it participates in the activation of Raf and other kinases, most likely through a phosphorylation mechanism. Once activated, Raf and other kinases phosphorylate MEK on two closely adjacent serine residues, S218 and S222 in the case of MEK-1, which are the prerequisite for activation of MEK as a kinase. MEK in turn phosphorylates MAP kinase on both a tyro sine, Y185, and a threonine residue, T183, separated by a single amino acid. This double phosphorylation activates MAP kinase at least 100-fold, and it can now catalyze the phosphorylation of a large number of proteins, including several transcription factors and other kinases. Many of these MAP kinase phosphorylations are mitogenically activating for the target protein, whether it be another kinase, a transcription factor, or other cellular protein. MEK is also activated by several kinases other than Raf-1, including MEKK, and itself appears to be a signal integrating kinase. As far as is currently known, MEK is highly specific for the phosphorylation of MAP kinase. In fact, no substrate for MEK other than MAP kinase has been demonstrated to date, and MEK does not phosphorylate peptides based on the MAP kinase phosphorylation sequence, or even phosphorylate denatured MAP kinase. MEK also appears to associate strongly with MAP kinase prior to phosphorylating it, suggesting that phosphorylation of MAP kinase by MEK may require a prior strong interaction between the two proteins. Both this requirement and the unusual specificity of MEK are suggestive that it may have enough difference in its mechanism of action to other protein kinases that selective inhibitors of MEK, possibly operating through allosteric mechanisms rather than through the usual blockade of the ATP binding site, may be found.
This invention provides compounds which are highly specific inhibitors of the kinase activity of MEK. Both in enzyme assays and whole cells, the compounds inhibit the phosphorylation of MAP kinase by MEK, thus preventing the activation of MAP kinase in cells in which the Ras cascade has been activated. The results of this enzyme inhibition include a reversal of transformed phenotype of some cell types, as measured both by the ability of the transformed cells to grow in an anchorage-independent manner and by the ability of some transformed cell lines to proliferate independently of external mitogens.
The compounds provided by this invention are 2-(phenylamino)benzoic acid, tetrazole, ester, amide, and benzyl alcohol derivatives, in which the phenyl ring is substituted at the 4-position with bromo or iodo. U.S. Pat. No. 5,155,110 discloses a wide variety of fenamic acid derivatives, including certain 2-(phenylamino)benzoic acid derivatives, as anti-inflammatory agents. The reference fails to describe the compounds of this invention or their kinase inhibitory activity.
This invention provides 4-bromo and 4-iodo phenylamino benzoic acid derivatives which are selective MEK kinase inhibitors and as such are useful for treating proliferative diseases such as cancer, psoriasis, and restenosis. The compounds are defined by Formula I 
wherein
R1 is hydrogen, hydroxy, C1-C8 alkyl, C1-C8 alkoxy, halo, trifluoromethyl, or CN;
R2 is hydrogen;
R3, R4, and R5 independently are hydrogen, hydroxy, halo, trifluoromethyl, C1-C8 alkyl C1-C8 alkoxy, nitro, CN, or xe2x80x94(O or NH)mxe2x80x94(CH2)nxe2x80x94R9, where R9 is hydrogen, hydroxy, CO2H, or NR10R11;
n is 0-4;
m is 0 or 1;
R10 and R11 independently are hydrogen or C1-C8 alkyl, or taken together with the nitrogen to which they are attached, can complete a 3-10 member cyclic ring optionally containing one, two, or three additional heteroatoms selected from O, S, NH, or Nxe2x80x94C1-C8 alkyl;
Z is COOR7, tetrazolyl, CONR6R7, CONHNR10R11, or CH2OR7;
R6 and R7 independently are hydrogen, C1-C8 alkyl, C2-C8 alkenyl, 
xe2x80x83aryl, heteroaryl, C3-C10 cycloalkyl, or C3-C10 (cycloalkyl optionally containing one, two, or three heteroatoms selected from O, S, NH, or N alkyl); or R6 and R7 together with the nitrogen to which they are attached complete a 3-10 member cyclic ring optionally containing 1, 2, or 3 additional heteroatoms selected from O, S, NH, or N alkyl;
and wherein any of the foregoing alkyl, alkenyl, and alkynyl groups can be unsubstituted or substituted by halo, hydroxy, alkoxy, amino, alkylamino, dialkylamino, cycloalkyl, aryl, aryloxy, heteroaryl, or heteroaryloxy, and the pharmaceutically acceptable salts thereof.
Preferred compounds have Formula II 
where R1, R3, R4, R5, R6, and R7 are as defined above. Especially preferred are compounds wherein R1 is methyl or halo, and R3, R4, and R5 are halo such as fluoro or bromo.
The compounds of Formula II are carboxylic acids when R7 is hydrogen, and are esters when R7 is other than hydrogen. Compounds which are analogous to the acids in physical and biological properties are tetrazolyl derivatives of Formula IIa 
Another preferred group of compounds are amides Formula III 
and hydrazides of Formula IIIa 
The benzyl alcohols of the invention have Formula IV 
The most preferred compounds are those wherein R1 is methyl, R3 is hydrogen or halo such as fluoro, R4 is halo such as fluoro, and R5 is hydrogen or halo such as fluoro, bromo, or chloro. Representative compounds have the formulas 
This invention also provides pharmaceutical formulations comprising a compound of Formula I together with a pharmaceutically acceptable excipient, diluent, or carrier. Preferred formulations include any of the foregoing preferred compounds together with an excipient, diluent, or carrier.
The compounds of Formula I are potent and selective inhibitors of MEK1 and MEK2 kinase enzymes. They are, therefore, useful to treat subjects suffering from cancer, stroke, diabetes, Alzheimer""s disease, cystic fibrosis, viral disease, heart failure, and proliferative diseases such as psoriasis, restenosis, autoimmune disease, and atherosclerosis. The compounds are especially well suited to treat cancers such as breast cancer, colon cancer, prostate cancer, skin cancer, and pancreatic cancer. They are particularly well-suited for use in conjunction with conventional radiation therapy. The compounds are also immunomodulatory agents and can be used to treat degenerative diseases where change in MEK activation leads to pathologies such as hepatomegaly and cardiomegaly. The invention provides a method of inhibiting MEK enzymes and the foregoing diseases by administering to a subject an effective amount of a compound of Formula I.
As used herein, the term xe2x80x9carylxe2x80x9d means a cyclic, bicyclic, or tricyclic aromatic ring moiety having from five to twelve carbon atoms. Examples of typical aryl groups include phenyl, naphthyl, and fluorenyl. The aryl may be substituted by one, two, or three groups selected from fluoro, chloro, bromo, iodo, alkyl, hydroxy, alkoxy, nitro, amino, alkylamino, or dialkylamino. Typical substituted aryl groups include 3-fluorophenyl, 3,5-dimethoxyphenyl, 4-nitronaphthyl, 2-methyl-4-chloro-7-aminofluorenyl, and the like.
The term xe2x80x9caryloxyxe2x80x9d means an aryl group bonded through an oxygen atom, for example phenoxy, 3-bromophenoxy, naphthyloxy, and 4-methyl-1-fluorenyloxy.
xe2x80x9cHeteroarylxe2x80x9d means a cyclic, bicyclic, or tricyclic aromatic ring moiety having from four to eleven carbon atoms and one, two, or three heteroatoms selected from O, S, or N. Examples include furyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, thiazolyl, oxazolyl, xanthenyl, pyronyl, indolyl, pyrimidyl, naphthyridyl, pyridyl, benzinnidazolyl, and triazinyl. The heteroaryl groups can be unsubstituted or substituted by one, two, or three groups selected from fluoro, chloro, bromo, iodo, alkyl, hydroxy, alkoxy, nitro, amino, alkylamino, or dialkylamino. Examples of substituted heteroaryl groups include chloropyranyl, methylthienyl, fluoropyridyl, amino-1,4-benzisoxazinyl, nitroisoquinolinyl, and hydroxyindolyl.
The heteroaryl groups can be bonded through oxygen to make heteroaryloxy groups, for example thienyloxy, isothiazolyloxy, benzofuranyloxy, pyridyloxy, and 4-methylisoquinolinyloxy.
The term xe2x80x9cC1-C8 alkylxe2x80x9d means straight and branched chain aliphatic groups having from one to eight carbon atoms, preferably one to four. Typical C1-C8 alkyl groups include methyl, ethyl, isopropyl, tert.-butyl, 2,3-dimethylhexyl, and 1,1-dimethylpentyl. The alkyl groups can be unsubstituted or substituted by halo, hydroxy, alkoxy, amino, alkylamino, dialkylamino, cycloalkyl, aryl, aryloxy, heteroaryl, or heteroaryloxy, as those terms are defined herein. Typical substituted alkyl groups include chloromethyl, 3-hydroxypropyl, 2-dimethylaminobutyl, and 2-(hydroxymethylamino)ethyl. Examples of aryl and aryloxy substituted alkyl groups include phenylmethyl, 2-phenylethyl, 3-chlorophenylmethyl, 1,1-dimethyl-3-(2-nitrophenoxy)butyl, and 3,4,5-trifluoronaphthylmethyl. Examples of alkyl groups substituted by a heteroaryl or heteroaryloxy group include thienylmethyl, 2-furylethyl, 6-furyloxyoctyl, 4-methylquinolyloxymethyl, and 6-isothiazolylhexyl. Cycloalkyl substituted alkyl groups include cyclopropylmethyl, 2-cyclohexyethyl, piperidyl-2-methyl, 2-(piperidin-1-yl)-ethyl, 3-(morpholin-4-yl)propyl.
xe2x80x9cC2-C8 Alkenylxe2x80x9d means a straight or branched carbon chain having one or more double bonds. Examples include but-2-enyl, 2-methyl-prop-2-enyl, 1,1-dimethyl-hex-4-enyl, 3-ethyl-4-methyl-pent-2-enyl, and 3-isopropyl-pent-4-enyl. The alkenyl groups can be substituted with halo, hydroxy, alkoxy, amino, alkylamino, dialkylamino, aryl, aryloxy, heteroaryl, or heteroyloxy, for example 2-bromoethenyl, 3-hydroxy-2-butenyl, 1-aminoethenyl, 3-phenylprop-2-enyl, 6-thienyl-hex-2-enyl, 2-furyloxy-but-2-enyl, and 4-naphthyloxy-hex-2-enyl.
xe2x80x9cC2-C8 Alkynylxe2x80x9d means a straight or branched carbon chain having from two to eight carbon atoms and at least one triple bond. Typical alkynyl groups include prop-2-ynyl, 2-methyl-hex-5-ynyl, 3,4-dimethyl-hex-5-ynyl, and 2-ethyl-but-3-ynyl. The alkynyl groups can be substituted as the alkyl and alkenyl groups, for example, by aryl, aryloxy, heteroaryl, or heteroaryloxy, for example 4-(2-fluorophenyl)-but-3-ynyl, 3-methyl-5-thienylpent4-ynyl, 3-phenoxy-hex-4-ynyl, and 2-furyloxy-3-methyl-hex-4-ynyl.
The alkenyl and alkynyl groups can have one or more double bonds or triple bonds, respectively, or a combination of double and triple bonds. For example, typical groups having both double and triple bonds include hex-2-en-4-ynyl, 3-methyl-5-phenylpent-2-en-4-ynyl, and 3-thienyloxy-hex-3-en-5-ynyl.
The term xe2x80x9cC3-C10 cycloalkylxe2x80x9d means a nonaromatic ring or fused rings containing from three to ten carbon atoms. Examples include cyclopropyl, cyclobutyl, cyclopenyl, cyclooctyl, bicycloheptyl, adamantly, and cyclohexyl. The ring can optionally contain one, two, or three heteroatoms selected from O, S, or NR9. Such groups include tetrahydrofuryl, tetrahydropyrrolyl, octahydrobenzofuranyl, morpholinyl, piperazinyl, pyrrolidinyl, piperidinyl, octahydroindolyl, and octahydrobenzothiofuranyl. The cycloalkyl groups can be substituted with the same substituents as an alkyl and alkenyl groups, for example, halo, hydroxy, aryl, and heteroaryloxy. Examples include 3-hydroxycyclohexyl, 2-aminocyclopropyl, 2-phenylpyrrolidinyl, and 3-thienylmorpholine-1-yl.
R6 and R7 can be taken together with the nitrogen to which they are attached to complete a cyclic ring having from 3 to 10 members, which may contain 1, 2, or 3 additional heteroatoms selected from O, S, NH, or N alkyl. Examples of such cyclic rings include piperazinyl, piperidyl, pyrrolidinyl, morpholino, N-methylpiperazinyl, aziridynyl, and the like. Such rings can be substituted with halo, hydroxy, alkyl, alkoxy, amino, alkyl, and dialkylamino, aryl, aryloxy, heteroaryl, and heteroaryloxy. Typical examples include 3-hydroxy-pyrrolidinyl, 2-fluoro-piperindyl, 4-(2-hydroxyethyl)-piperidinyl, and 3-thienylmorpholino.
The 2-(4-bromo and 4-iodo phenylamino)-benzoic acid derivatives of Formula I can be prepared from commercially available starting materials utilizing synthetic methodologies well-known to those skilled in organic chemistry. A typical synthesis is carried out by reacting a 4-bromo or 4-iodo aniline with a benzoic acid having a leaving group at the 2-position to give a 2-(phenylamino)-benzoic acid. This process is depicted in Scheme 1. 
where L is a leaving group, for example halo such as fluoro.
The reaction of aniline and the benzoic acid derivative generally is accomplished by mixing the benzoic acid with an equimolar quantity or excess of the aniline in an unreactive organic solvent such as tetrahydrofuran or toluene, in the presence of a base such as lithium diisopropylamide, n-butyl lithium, sodium hydride, triethylamine, and Hunig""s base. The reaction generally is carried out at a temperature of about xe2x88x9278xc2x0 C. to about 100xc2x0 C., and normally is complete within about 2 hours to about 4 days. The product can be isolated by removing the solvent, for example by evaporation under reduced pressure, and further purified, if desired, by standard methods such as chromatography, crystallization, or distillation.
The 2-(phenylamino)-benzoic acid (eg, Formula I, where R7 is hydrogen) can be reacted with an organic or inorganic base such as pyridine, triethylamine, calcium carbonate, or sodium hydroxide to produce a pharmaceutically acceptable salt. The free acids can also be reacted with an alcohol of the formula HOR7 (where R7 is other than hydrogen, for example methyl) to produce the corresponding ester. Reaction of the benzoic acid with an alcohol can be carried out in the presence of a coupling agent. Typical coupling reagents include 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ), 1,3-dicyclohexylcarbodiimide (DCC), bromo-tris(pyrrolidino)-phosphonium hexafluorophosphate (PyBrOP), and (benzotriazolyloxy)tripyrrolidino phosphonium hexafluorophosphate (PyBOP). The phenylamino benzoic acid and alcohol derivative normally are mixed in approximately equimolar quantities in an unreactive organic solvent such as dichloromethane, tetrahydrofuran, chloroform, or xylene, and an equimolar quantity of the coupling reagent is added. A base such as triethylamine or diisopropylethylamine can be added to act as an acid scavenger if desired. The coupling reaction generally is complete after about 10 minutes to 2 hours, and the product is readily isolated by removing the reaction solvent, for instance by evaporation under reduced pressure, and purifying the product by standard methods such as chromatography or crystallizations from solvents such as acetone, diethyl ether, or ethanol.
The benzamides of the invention, Formula I where Z is CONR6R7, are readily prepared by reacting the foregoing benzoic acids with an amine of the formula HNR6R7. The reaction is carried out by reacting approximately equimolar quantities of the benzoic acid and amine in an unreactive organic solvent in the presence of a coupling reagent. Typical solvents are chloroform, dichloromethane, tetrahydrofuran, benzene, toluene, and xylene. Typical coupling reagents include DCC, EEDQ, PyBrOP, and PyBOP. The reaction is generally complete after about 10 minutes to about 2 hours when carried out at a temperature of about 0xc2x0 C. to about 60xc2x0 C. The product amide is readily isolated by removing the reaction solvent, for instance by evaporation, and further purification can be accomplished by normal methods such as chromatography, crystallization, or distillation. The hydrazides (z=CONHNR10R11) are similarly prepared by coupling a benzoic acid with a hydrazine of the formula H2HNR10R11.
The benzyl alcohols of the invention, compounds of Formula I where Z is CH2OR6 and R6 is hydrogen, are readily prepared by reduction of the corresponding benzoic acid according to the following scheme 
Typical reducing agents commonly employed include borane in tetrahydrofuran. The reduction normally is carried out in an unreactive organic solvent such as tetrahydrofuran, and generally is complete within about 2 hours to about 24 hours when conducted at a temperature of about 0xc2x0 C. to about 40xc2x0 C.
The following detailed examples illustrate specific compounds provided by this invention.